The Mariah Owners Club

The Mariah Owners Club (http://www.mariahownersclub.com/forum/)
-   Prop Talk (http://www.mariahownersclub.com/forum/prop-talk/)
-   -   Need lower end power but rpms already high (http://www.mariahownersclub.com/forum/prop-talk/4552-need-lower-end-power-but-rpms-already-high.html)

jefros 07-24-2010 12:32 PM

Need lower end power but rpms already high
 
I have a 1999 Jubille 214 with the 5.7 Alpha. Current prop is a Michigan Wheel Apollo SS 21p 3blade. Top speed is about 47mph but it it is turning 5300-5400 rpms which seems high. The problem is that I want better hole shot and slower planing speeds for skiing/wakeboarding. My choices seem to be either dropping to a 19p 3 blade or a 18p or 20p 4 blade. But..wont this raise my rpms higher then what seems to be already too high (obviously I can just back off from full throttle at top end as needed.) I am leaning toward maybe the 20p 4 blade and then adding smart tabs. What do you guys think? Thanks in advance!

DougR 07-24-2010 02:14 PM

Re: Need lower end power but rpms already high
 
Try a 4 blade at 21p that should help a little.....

mikeyt 07-24-2010 05:05 PM

Re: Need lower end power but rpms already high
 
Your recommended rpm range is 4400-4800 at WOT for that engine so if it is really running at 5300-5400 with a 21" pitch then something is wrong. First, i would check to see that the tach is set correctly. Gain access to the rear of your tach & give the little dial a spin around a couple of times before setting back on "8 cyl" then test run it to see if it still reads that high. If i remember correctly the 5.7 came with a number of different outdrive ratios so that might affect your readings. Normally i would suggest a drop to a 19 - 3blade or a 20" - 4blade to give a better holeshot but that will increase your rpms. Unfortunately going with a 4 blade 21" will increase your rpms slightly too as would any drop in pitch so i suggest that you ensure the tach is reading correctly first.

jefros 07-25-2010 02:16 AM

Re: Need lower end power but rpms already high
 
Thanks for the reply. I agree, something does not seem right. The tach is an aftermarket unit since my original Faria unit died. I will check the setting. Either way, would you recommend a 19p 3 blade or a 20p 4 blade (or 18p 4 blade?) if you were going to try something different. Thanks

al levy 09-04-2010 04:42 AM

Re: Need lower end power but rpms already high
 
4 blade is always good however if i remember correctly the apollo props come with a terrible cup. have your prop man really cup the prop and have it run into and around the trailing edge. this will lower the rpms but may give more speed as you will be able to usually trim the boat more. as far as getting out of the water better have your prop man punch pitch which can lower the leading edge down to a 19 or even 18. this wil not affect the mid range of top end.
if you know your only skiing or running a heavy load use a four blade that day or switch to a ss 4 blade. should know gear ratio


All times are GMT. The time now is 01:21 AM.